I'll try to explain what I'm thinking.,
My picture is a little crude.
The yellow line represents the distance between the arms, 16.5cm. The blue line is the length of a crank arm, 17cm. The crank is almost as wide as the length of the crank arm. The red line represents the length from the end of the threads to the crank arm, 4cm. The Sunlight crank is 15.5 cm, it won't work. The dimensions are on both sides of the crank. 170mm crank length and 161mm width, I measured 165mm.
If you want the one piece crank and are having trouble finding it,
Take your broken crank to a bicycle shop and have them find a crank for you
I'm sure they can find one like the Whizzer crank or a wide one piece crank set or a wide 3 piece crank set
BTW it's best to buy all new parts (crank set) when replacing a crank